The Effect of Asphyxia upon the Lactate, Pyruvate and Bicarbonate Concentrations of Brain Tissue and Cisternal CSF, and upon the Tissue Concentrations of Phosphocreatine and Adenine Nucleotides in Anesthetized Rats

Abstract

Abstract K aasik , A. E., L. N ilsson and B. K. S iesjö . The effect of asphyxia upon the lactate, pyruvate and bicarbonate concentrations of brain tissue and cisternal CSF, and upon the tissue concentrations of phosphocreatine and adenine nucleotides in anesthetized rats . Acta physiol. scand. 1970. 78 . 433–447. The effect of asphyxia upon the lactate, pyruvate and bicarbonate concentrations of brain tissue and cisternal CSF, and upon the tissue concentrations of phosphocreatine, ATP, ADP and AMP was studied in anesthetized and curarized rats, both at various times during (1, 2, 3 and 4 min) respiratory arrest, and after (1, 2, 5, 10 and 60 min) an arrest of 3 min. After 3 min of asphyxia the intracellular lactate concentration had increased to about 22 mMol/kg of i.c. water, while the calculated pHi' had decreased about 0.6 units to 6.50. At the same time almost all phosphocreatine had disappeared, and AMP had increased about tenfold, while there were clearcut, although less drastic, changes in AIP and 4DP. When the asphyxia was prolonged to 4 min the pH reduction apparently inhibited further glucolysis, and asphyxiawasa further fall in pHi'. Upon resumption of ventilation, the ATP, ADP and AMP concentrations, and the calculated cytoplasmatic NADH/NAD+ ratio, normalized within 2 min, and the phosphocreatine concentration as well as the sum of the adenine nucleotides within 5 min, while almost all excess lactate and pyruvate had disappeared within 10 min. There was a gradual and slow normalization of the calculated intracellular pHi' and the tissue was still acid 10 min after restarting the respirator. The three min period of asphyxia was associated with a rapid and marked lactacidosis in arterial blood which was normalized at 60, but not at 10 min. In the CSF, the lactacidosis developed gradually during several min, and the lactate concentration had not normalized until in the 60 min group.